For the first time, the Northwestern researchers used the P300 testing in a mock terrorism scenario in which the subjects are planning, rather than perpetrating, a crime. The P300 brain waves were measured by electrodes attached to the scalp of the make-believe “persons of interest” in the lab.

The most intriguing part of the study in terms of real-word implications, Rosenfeld said, is that even when the researchers had no advance details about mock terrorism plans, the technology was still accurate in identifying critical concealed information.

“Without any prior knowledge of the planned crime in our mock terrorism scenarios, we were able to identify 10 out of 12 terrorists and, among them, 20 out of 30 crime- related details,” Rosenfeld said. “The test was 83 percent accurate in predicting concealed knowledge, suggesting that our complex protocol could identify future terrorist activity.”

Rosenfeld is a leading scholar in the study of P300 testing to reveal concealed information. Basically, electrodes are attached to the scalp to record P300 brain activity — or brief electrical patterns in the cortex — that occur, according to the research, when meaningful information is presented to a person with “guilty knowledge.”

Research on the P300 testing emerged in the 1980s as a handful of scientists looked for an alternative to polygraph tests for lie detection. Since it was invented in the 1920s, polygraphy has been under fire, especially by academics, with critics insisting that such testing measures emotion rather than knowledge.

University press releases about new research tend to promise more than the research subsequently delivers, of course. Check back in a few years and we’ll see if this turned into an actual technology; if so, there will be a number of legal questions involved. I don’t have any expertise or background knowledge in this particular technology, and would be interested in comments from people who know something about it.